In chaos theory, the butterfly effect is the sensitive dependence on initial conditions in which a small change in one state of a deterministic nonlinear system can result in large differences in a later state.

Eric Cantona was the butterfly effect for Manchester United.

Having won the league in 1992, Leeds chairman Bill Fotherby called up Martin Edwards, United’s chairman, to enquire about the availability of Denis Irwin. Sir Alex Ferguson told Edwards that Irwin was not for sale but he did like the look of their striker, Eric Cantona. Before the days of the transfer window, United were able to sign the Frenchman as cover for Dion Dublin who had broken his leg early in to the 1992-93 season. United were 8th in the table at the end of November when the deal was done.

Nobody could have predicted what the consequences of this signing would be and it’s difficult, even now, to calculate just how far-reaching the implications have been.

United won the title in Cantona’s debut season at the club, our first for 26 years, 10 points ahead of second-placed Aston Villa.

While it would be unfair to credit him solely for that title win, after Ferguson had built a team that had come so close the season before, there’s no denying that Cantona was the missing piece of the jigsaw, the sort of inspiration we’re so desperately craving right now.

“He just had that aura and presence,” Paul Ince later reflected. “He took responsibility away from us. It was like he said: ‘I’m Eric, and I’m here to win the title for you’.”

The following season, United won the Double. The season after, Eric found himself suspended for the run in after kicking a racist and United lost out on another Double by a point to Blackburn in the league and a goal against Everton in the FA Cup final.

When he returned for the following campaign, United won the Double again. The year after, the league title. And then, with years of football still left in him, Cantona retired.

It would be fair to argue that Cantona’s impact in those five years was greater than anything we’ve seen over the past few decades at least (six years if you count his achievements at Leeds the season before). Four league titles and two FA Cups for United isn’t a bad return. Yet it would be doing him a disservice to claim that those six trophies is all the club has to thank him for. You cannot underestimate the influence he had on the years of glory that followed his retirement.

Gary Pallister, who won 10 major trophies with United, recalled the impact that Cantona’s signing had on the club.

We had a very strong team spirit and some great personalities and characters. But Eric just walked in with that straight-back stance as if to say, ‘I was born for this place.’ Being a character is one thing but to carry it off you have to have the ability to go with it. Eric did.

We were a professional squad but Eric brought a new professionalism to the club. It was unique. He started training before us and stayed out longer than anyone else. It was a real eye-opener. It had a big effect on us and I also know how much it impacted on the Class of ’92. The likes of David Beckham, Paul Scholes, Nicky Butt and Gary Neville learnt so much from Eric and his professionalism.

Alan Hansen infamously claimed you’d never win anything with kids. Maybe he would have been right. If Cantona wasn’t at the club, maybe those comments following United’s 3-1 defeat against Villa on the opening day of the 1995-96 wouldn’t have been written in to Premier League folklore.

The Class of ’92, as they are now branded, saw a winning mentality ingrained in the club thanks to the Frenchman. The way they applied themselves, how hard they worked, and the skill they possessed, was like nothing the club had seen since the Busby Babes. Yet if they hadn’t won the Double in their debut season in the first team, would they have had the self-belief required to win the unprecedented Treble? He had been gone for one season before they began that magical journey to the promised land, as they approached their peak, that separates United from all other English clubs. That team didn’t know when they were beaten, coming back against all odds time and again to claim all three major trophies in the 1998-99 season. Would that have happened if they hadn’t been inspired by Cantona during their breakthrough years?

And that team inspired the next generation. Cristiano Ronaldo, Wayne Rooney and co. all hail the likes of Ryan Giggs, David Beckham and Paul Scholes as their footballing heroes. Plenty more league titles, a few more domestic cups and another Champions League followed.

There’s no science to this. The direction of the club can’t be calculated accurately with or without Cantona. But what we know for certain is that his presence at United had an unmeasurably positively influence that is further reaching than we probably realise.

What is interesting though, having read Cantona’s excellent piece for The Player’s Tribune, is that butterfly effect began long before we realised.

Cantona’s maternal grandfather, Pere Raurich, was Spanish and was fighting the armies of General Franco in the Spanish Civil War in 1938. He suffered a serious injury to his liver and had to retreat to France for medical treatment. Cantona tells the tale:

At the very end of the war, he was a wanted man, and he only had a few minutes to make an escape before the Nationalist soldiers captured the city. He had to cross the Pyrenees mountains on foot to get to France, and he did not have time to say proper goodbyes. This was the end. Life or death.

So before he left, he went to find his girlfriend, and he asked her, “Are you ready to follow me?”

He was 28 years old. She was 18. She had to leave behind her family, friends, everything.

But she said, “Yes, of course.”

This was my grandmother.

Imagine if his grandmother, Paquita, got cold feet. Imagine if she wasn’t prepared to leave her family. Imagine if she didn’t love Pere as much as he thought. He goes to France alone, maybe falls in love with someone else and has children with her, and Eric’s mother is never born. Eric is never born. United aren’t inspired to their first title win in 26 years in 1993. They don’t win the Treble in 1999. They don’t inspire a whole generation of footballers who are desperate to pull on United’s shirt and win a record-breaking number of league titles.

Cantona continues:

This is the life of immigrants. You go where you must. You do what you must. So they went. They made a life for themselves. Imagine if my grandfather had not made it. Imagine if my grandmother had not followed him. Maybe then my mother would not exist. Maybe then I would not exist.

Here’s to you, Paquita, for falling in love, leaving your family, and making my life immeasurably better than it otherwise would have been.

“Until my last dying breath, I will have Manchester United in my heart.” – Cantona, the King.